Explain the type of reactions represented by the following equations:
$(i)$ $CaO + CO_2 \longrightarrow CaCO_3$
$(ii)$ $2Na + 2H_2O \longrightarrow 2NaOH + H_2$

(N/A) $(i)$ Combination reaction: In this reaction,two or more reactants combine to form a single product. Here,calcium oxide $(CaO)$ reacts with carbon dioxide $(CO_2)$ to form a single product,calcium carbonate $(CaCO_3)$.
$(ii)$ Displacement reaction: In this reaction,a more reactive element displaces a less reactive element from its compound. Here,sodium $(Na)$ displaces hydrogen from water $(H_2O)$ to form sodium hydroxide $(NaOH)$ and releases hydrogen gas $(H_2)$.